U.S. patent number 5,733,219 [Application Number 08/648,525] was granted by the patent office on 1998-03-31 for apparatus and method for disabling a compression brake system.
This patent grant is currently assigned to Caterpillar Inc.. Invention is credited to Mark E. Rettig, Thomas R. Sandborg.
United States Patent |
5,733,219 |
Rettig , et al. |
March 31, 1998 |
Apparatus and method for disabling a compression brake system
Abstract
An apparatus is provided for controlling a compression brake on
an internal combustion engine. the apparatus includes means for
automatically disabling the compression brake once the vehicle
speed falls below a predetermined value.
Inventors: |
Rettig; Mark E. (Peoria,
IL), Sandborg; Thomas R. (Mapleton, IL) |
Assignee: |
Caterpillar Inc. (Peoria,
IL)
|
Family
ID: |
24601139 |
Appl.
No.: |
08/648,525 |
Filed: |
May 13, 1996 |
Current U.S.
Class: |
477/91; 123/322;
123/323; 477/107 |
Current CPC
Class: |
F02D
13/04 (20130101); Y10T 477/675 (20150115); Y10T
477/6437 (20150115) |
Current International
Class: |
F02D
13/04 (20060101); B60K 041/28 () |
Field of
Search: |
;477/90,91,92,107,181,295,196,198,201,202,204
;123/320,321,322,324 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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|
|
|
|
|
|
63-1725 |
|
Jan 1988 |
|
JP |
|
63-277827 |
|
Nov 1988 |
|
JP |
|
2-277931 |
|
Nov 1990 |
|
JP |
|
59-39944 |
|
Mar 1994 |
|
JP |
|
Primary Examiner: Ta; Khoi Q.
Attorney, Agent or Firm: Wilbur; R. Carl
Claims
We claim:
1. An apparatus for controlling the speed of a vehicle equipped
with an internal combustion engine, comprising:
an electronic controller;
a compression brake electrically connected to said electronic
controller and connected to said internal combustion engine;
vehicle speed sensing means, said vehicle speed sensing means
producing a vehicle speed signal responsive to a speed of said
vehicle;
wherein the electronic controller disables said compression brake
responsive to said vehicle speed; and
wherein the electronic controller disables said compression brake
in response to a vehicle speed signal falling below a predetermined
value.
2. An apparatus according to claim 1, including:
a data port connected to said electronic controller;
wherein said predetermined value is programmable and is programmed
using an external programming device, connected to said data
port.
3. An apparatus for controlling the speed of a vehicle equipped
with an internal combustion engine, comprising:
an electronic controller;
a compression brake electrically connected to said electronic
controller and connected to said internal combustion engine;
vehicle speed sensing means, said vehicle speed sensing means
producing a vehicle speed signal responsive to a speed of said
vehicle;
wherein the electronic controller disables said compression brake
responsive to said vehicle speed;
a first switch connected to said electronic controller;
said first switch having an on position, said compression brake
being enabled when said first switch is in the first position;
and
said compression brake being disabled when said vehicle speed
signal represents a vehicle speed less than said predetermined
value.
4. An apparatus for controlling the speed of a vehicle equipped
with an internal combustion engine, comprising:
an electronic controller;
a compression brake electrically connected to said electronic
controller and connected to said internal combustion engine;
vehicle speed sensing means, said vehicle speed sensing means
producing a vehicle speed signal responsive to a speed of said
vehicle;
wherein the electronic controller disables said compression brake
responsive to said vehicle speed;
a first switch having an on position;
an engine speed sensor connected to said electronic controller,
said engine speed sensor producing an engine speed signal;
a throttle connected to said engine;
a throttle position sensor connected to said throttle, said
throttle position sensor producing a desired throttle command;
a clutch pedal;
a clutch pedal sensor, said clutch pedal sensor producing a clutch
released signal when said clutch pedal is released; and
wherein said electronic controller engages said compression brake
when said first switch is in said on position, said engine speed is
greater than a predetermined engine speed, said desired throttle is
less than a predetermined throttle command, said clutch pedal
sensor produces a clutch released signal, and said vehicle speed is
greater than a predetermined vehicle speed.
5. An apparatus according to claim 4 wherein said electronic
controller disengages said engaged compression brake when said
engine speed is less than said predetermined engine speed, said
desired throttle is greater than said predetermined throttle
command, or said clutch pedal sensor produces a clutch depressed
signal.
6. An apparatus according to claim 4, including:
a second switch, said second switch being connected to said
electronic controller and having at least a first, second, and
third position; and
said compression braking produces a first, second and third level
of braking, responsive to the position of said second switch, when
said compression brake is engaged.
7. A method of operating a compression brake associated with an
internal combustion engine on a vehicle, said method comprising the
steps of:
determining the speed of the vehicle; and
disabling the compression brake in response to said vehicle speed
being less than a predetermined value.
8. A method of operating a compression brake associated with an
internal combustion engine on a vehicle, said method comprising the
steps of:
determining if the compression brake is enabled;
determining the engine speed;
comparing the engine speed to a predetermined engine speed;
determining a throttle command;
comparing the throttle command to a predetermined determined
throttle command;
determining whether a vehicle clutch pedal is realeased;
determining the speed of the vehicle;
comparing the vehicle speed to a predetermined vehicle speed;
and
engaging the compression brake in response to the compression brake
being enabled, the engine speed being greater than the
predetermined engine speed, the throttle command being less than a
predetermined throttle command, the clutch pedal being released and
the vehicle speed being less than the predetermined vehicle
speed.
9. The method according to claim 8, after said step of engaging,
including the step of:
disengaging the compression brake in response to either the engine
speed being less than the predetermined engine speed, the throttle
command being greater than a predetermined throttle command, or the
clutch being depressed.
Description
TECHNICAL FIELD OF THE INVENTION
The present invention relates generally to electronically
controlled engines and, more particularly, to an electronically
controlled engine equipped with a compression braking system.
BACKGROUND ART
Vehicles such as on-highway trucks often use compression brakes to
assist in slowing the vehicle, without operating the vehicle
service brakes. A compression brake slows the vehicle by
manipulating the intake and exhaust valves to remove energy from
the engine. Typically, the compression brake permits air to enter
the cylinder during the intake cycle, and allows the engine to
compress the air as the piston moves toward top dead center.
Compressing the air transfers work from the piston to the
compressed air. That work is then released as the piston reaches
top dead center by opening the exhaust valve. In this manner the
work required to compress the air is then expelled and a
corresponding retarding force is transmitted through the
transmission to the rear wheels thereby assisting in slowing the
vehicle.
When the compression brake is operating, it typically is very
noisy. The noise results from opening the exhaust valve and quickly
releasing the compressed air. In some instances the noise may be
objectionable to the vehicle operator. In other instances cities
and towns have enacted regulations prohibiting the use compression
brakes within the city limits. In those cases, operators that use a
compression brake within city limits are subject to fines.
Typically there is a dash-mounted switch within the vehicle that
permits the operator to enable or disable the compression brake
system. Generally there is also an additional switch that controls
the number of cylinders involved in the compression braking and
therefore controls the braking force produced by the compression
braking system. To avoid the fines that may result from using the
compression brake within city limits, a vehicle operator must
manually disable the braking system using the dash-mounted switch.
However, because the braking system is only engaged under certain
operating conditions, the operator may not be aware that the
compression brake is enabled until the brake actually engages. At
that point the braking system will have already emitted the noise
and the operator may have been fined.
The present invention is directly toward overcoming one or more of
the drawbacks associated with prior art compression braking
systems.
SUMMARY OF THE INVENTION
In one aspect of the present invention an apparatus is disclosed
for controlling the speed of a vehicle equipped with an internal
combustion engine and a compression braking system. The apparatus
includes a vehicle speed sensor which is connected to an electronic
controller. The vehicle speed sensor produces a vehicle speed
signal and the electronic controller disables the compression
braking system as a function of the vehicle speed signal.
In another aspect of the present invention, a method of operating a
compression brake on an internal combustion engine in a vehicle is
disclosed. The method includes the steps of determining the speed
of the vehicle and disabling the compression brake in response to
the step of determining the speed of the vehicle.
These and other aspects of the present invention will become
apparent upon reading the detailed description of the preferred
embodiment in conjunction with the drawings and appended
claims.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram of the various components and connections
associated with a preferred embodiment of the present
invention.
FIG. 2 is a flowchart of software associated with an embodiment of
the invention.
FIG. 3 is a flowchart of a preferred embodiment of the software
associated with the invention.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
Referring first to FIG. 1, a preferred embodiment of the
compression brake control system 10 of the present invention is
shown in block diagram form. The compression brake control system
10 preferably includes a compression brake 15 connected to the
engine 20. The connection between the compression brake and the
engine is known to those skilled in the art. The connection between
the compression brake 15 and the engine 20 will therefore not be
discussed herein. The engine 20 is connected to a transmission 25
that drives a rear axle (not shown) which in turn drives the rear
wheels or other propulsion means of the vehicle.
An electronic control module 35 ("ECM") is connected to solenoids
36, 37, 38 which are associated with and drive components in the
compression brake 15 to cause the compression brake 15 to engage.
The ECM 35 is also connected to a clutch position sensor 40
associated with a clutch pedal 45 in the operator compartment of
the vehicle. In a preferred embodiment, the clutch sensor 40
includes a two-position switch that produces a first signal when
the clutch pedal is fully depressed and the clutch is engaged and a
second signal when the clutch pedal is not depressed and the clutch
is disengaged. However, any suitable sensor that outputs a position
signal may be used without deviating from the scope of the present
invention.
The ECM 35 is also connected by connector 51 to a throttle position
sensor 50 associated with a throttle pedal 55 preferably located in
the operator compartment of the vehicle. In a preferred embodiment,
the throttle pedal position sensor 50 is a potentiometer type
device as disclosed in U.S. Pat. No. 4,915,075 issued to Brown.
However, other suitable position sensors are known in the art and
may be readily and easily substituted for the position sensor
disclosed in Brown, without deviating from the scope of the present
invention as defined by the appended claims. The ECM is also
electrically connected to a engine speed sensor 60. The engine
speed sensor preferably includes a magnetic pick up sensor adapted
to produce a signal corresponding to the rotational speed of the
engine 20. One suitable sensor is disclosed in U.S. Pat. No.
4,972,332 which issued to Luebbering et al. on Nov. 20, 1990. The
sensor 60 produces a signal on electrical connector 65 whose
frequency is a function of engine speed.
The ECM is also electrically connected to a vehicle speed sensor 30
by electrical connector 70. In a preferred embodiment, the vehicle
speed sensor 30 is a magnetic pick up sensor as described above.
The vehicle speed sensor 30 is preferably located adjacent to an
output of the transmission 25 and senses a gear tooth or teeth in
the transmission 25. The vehicle speed sensor 60 produces a signal
on connector 70 whose frequency is a function of the transmission
output speed. The rear axle ratio and the tire size of the vehicle
are typically stored in memory. Using those values the ECM 35 is
able to calculate the vehicle speed as a function of the vehicle
speed sensor 60 signal.
The ECM 35 is also connected to a compression brake switch 75. In
preferred embodiment the compression braking switch 75 includes a
two-position switch 77 having an "on" position and an "off"
position. When the compression brake engaged switch 75 is in an on
position, the ECM 35 enables the compression brake 15. Thereafter,
and as is described more fully below with respect to FIG. 2, the
compression brake 15 will be engaged under certain vehicle
operating conditions.
Also connected to the ECM is a compression braking level switch 80.
In a preferred embodiment the compression braking level switch 80
includes a three-position switch 85. Each of the three positions of
switch 85 corresponds to a specific braking level output from the
compression brake 15. For example if the switch 85 is in a first
position, the ECM may energize solenoid 36 thereby causing two
engine cylinders to perform the braking. If the switch 85 is in a
second position, the ECM may energize solenoids 36,37 thereby
causing four engine cylinders to perform engine braking. Finally,
if the switch 85 is in a third position the ECM 35 may energize
solenoids 36,37,38 thereby causing six engine cylinders to perform
engine braking 15. As is known to those skilled in the art,
increasing the number of engine cylinders performing engine braking
increases the braking force exerted by the engine through the
transmission to the rear wheels. Although FIG. 1 illustrates a
three-position switch 85 and three solenoids 36,37,38 it will be
recognized to those skilled in the art that the number of solenoids
may be readily and easily varied and the number of positions on the
compression braking level switch 80 may be varied without deviating
from the scope of the present invention. For example, if an engine
has eight cylinders a suitable compression brake 15 might include
four solenoids and a four-position switch, thereby providing the
vehicle operator with four different levels of engine braking.
As is known to those skilled in the art, the ECM 35 will generally
include a microprocessor 90 and memory 95. The memory 95 will
include both data 96 and software instructions 97 to perform the
control of a preferred embodiment of the present invention. The
software instructions are described in greater detail below in
flowchart form with reference to FIG. 2.
Also connected to the ECM 35 is a data input port 99. The data
input port may be an input jack or other similar connector to allow
an external programming device to input data into the memory 95.
Typically, the data inputs are governed by SAE Standard number
J1708 for on-highway trucks. Through the use of the data input port
99, a vehicle owner or fleet operator may input various data that
affect software control of the compression brake control system
10.
Referring now to FIG. 2 and FIG. 3, flowcharts showing the
microprocessor control performed according to the software
instructions stored in the instruction portion 97 of memory 95 are
shown. The detailed flowcharts depicted represent a complete and
workable design of preferred software programs and have been
reduced to practice on the Series MC68HC11 microprocessor
manufactured by Motorolla Semiconductors, Inc. located in Phoenix,
Ariz. Software may be readily and easily coded from this flowchart
using the instruction set associated with this microprocessor, or
the instruction set of other suitable microprocessors. Writing the
software from this flowchart is a mechanical step for one skilled
in the art.
In the first block 100, the ECM 35 reads the input signal on
electrical connector 76 from the compression brake switch 75. If
the signal on connector 76 corresponds to the switch being in an
"on" position then program control passes to block 105. Otherwise
program control passes to block 150, where the ECM disables the
compression brake 15.
In block 105, the ECM reads the engine speed signal produced by the
engine speed sensor 60 on electrical connector 65. The ECM 35
compares the engine speed to a predetermined engine speed stored in
memory 95. In a preferred embodiment the predetermined engine speed
is 800 rpm. However, this value may be readily and easily changed
for other engine 20 and compression brake 15 combinations. In block
105, if the engine speed as determined from the signal on connector
65 is less than or equal to the predetermined engine speed, then
program control passes to block 150 where the ECM disables the
compression brake 15. If, however, the engine speed is greater than
the predetermined engine speed, then control passes to block
110.
In block 110, the ECM 35 reads the signal produced by the throttle
pedal position sensor 50 on electrical connector 51. If the
throttle command as determined by the signal on the electrical
connector 51 is less than or equal to a predetermined throttle
command, then software control passes to block 120. Otherwise
software control passes to block 150 where the ECM 35 disables the
compression brake 15.
In block 120, the ECM 35 reads the signal produced by the clutch
pedal sensor 40 on electrical connector 41. If the signal on
produced by the clutch pedal sensor 40 electrical connector 41
corresponds to the clutch pedal being released then software
control passes to block 130, otherwise software control passes to
block 150 where the ECM 35 disables the compression brake 15.
In block 130, the ECM 35 reads the signal on electrical connector
70 and calculates a vehicle speed. The ECM compares the vehicle
speed to a programmed minimum vehicle speed stored in memory.
Although the programmed minimum vehicle speed might be a factory
default value programmed into memory that cannot be changed by the
vehicle owner, in a preferred embodiment the programmed minimum
vehicle speed is a programmable variable that can be controlled by
the vehicle owner or fleet manager. That value is programmed using
an external programming device connected to the data input port 99
and then stored in the data section 96 of memory 95. Alternatively,
the programmed minimum vehicle speed could be selected by the
vehicle operator through a dash display and selector. In block 130
the ECM compares the programmed minimum vehicle speed to the
vehicle speed calculated from the signal on electrical connector
70. If the vehicle speed is less than or equal the programmed
minimum vehicle speed then program control passes to block 150
where the ECM disables the compression brake. Otherwise software
control passes to block 140. In block 140, since the conditions of
blocks 100-130 have been satisfied, the compression brake 15 is
engaged. Block 140 program control returns to the beginning of the
control loop and verifies the condition of block 100. Likewise from
150 where the compression brake is disabled, program control
returns to the beginning of the program loop and begins the step of
block 100.
Referring now to FIG. 3, a flowchart for the software control of a
preferred embodiment is shown. The software control for this
embodiment uses the vehicle speed calculation as an initial
determinant in engaging or disengaging the compression brake. Like
the previous embodiment, if the vehicle speed is initially above
the programmed minimum vehicle speed and the other conditions of
blocks 200-230 are satisfied, then the compression brake is engaged
in block 140. However, this alternative embodiment operates
differently from the embodiment of FIG. 2 once the compression
brake has engaged. In this embodiment, the compression brake will
thereafter remain engaged irrespective of vehicle speed until one
of the other conditions cause it to disengage. Thus, as shown in
FIG. 3, the compression brake will remain engaged until the engine
speed falls below the predetermined engine speed, the brake switch
is turned off, the throttle is depressed or the clutch is
depressed. The order of the software instruction represented by
flowchart blocks 200-230 as shown in FIG. 3 is exemplary. The
specific order in which each of the conditions is performed is not
important so long as the overall flow and functionality shown in
the flowchart is maintained.
The present invention provides an advantage over prior art
compression brake control systems by providing the operator with an
automatic disabling feature once the vehicle speed drops below a
preprogrammed minimum vehicle speed. Thus, even though the operator
has the compression brake engaged using the switch 75, and all of
the conditions of software block 100, 105, 110,120 are satisfied,
the compression brake will nevertheless be disabled if the vehicle
speed is less than the preprogrammed minimum vehicle speed. Thus,
if the vehicle owner or fleet manager programs a minimum vehicle
speed corresponding to vehicle speeds at which the vehicle would be
traveling in a city, the control system 10 of the present invention
will automatically disable the compression brake 15 when the
vehicle speed corresponds to those speeds for city driving. In this
manner the operator may rely on the electronic control module to
automatically disable the compression brake and thereby avoid fines
and unwanted noise in conjested areas with heavy traffic.
* * * * *